Capacitive sensor systems can be realized by generating an alternating electrical field and measuring the potential difference (i.e., the voltage) obtained in one cycle at a sensor electrode within this field. A single electrode or a transmitting and one or more receiving electrodes may be used. This voltage is a measure for the capacitance between the sensor electrode and its electrical environment, i.e., it is influenced by objects like a human finger or a hand. Further, from this voltage, for example, the distance of a finger can be deduced. This information can be used for human-machine interfaces.
The problem with conventional systems operating according to the above-mentioned principle is that electrical noise sources, such as fluorescent lamps or USB chargers can affect the electrical field. Thus, accurately and reliably estimating this voltage in a noisy environment is problematic.